An inorganic flexible fibrous material consisting of the asbestos-like form of an alkali metal titanate and its preparation



- 2,833,620 AN INORGANIC FLELE FIBROUS MATERIAL CONSISTZNG on THEASBESTOS-LIKE FORM or AN ALKALI METAL 'TITANATE AND ITS PREP- AH NThurman E. Gier and Paul L. Salz'berg, Wilmington, Del and Howard S.Young, Chadds Ford, Pa., assignors to.E. I. du Pont de Nemours andCompany, Wilmington, Del.,' a corporation of Delaware "Nd Drawing.Application September 24, 1954 Serial No. 458,279

7 27 Claims. (Cl. 23-9-51 1 has been'described as producing othertitanates, suchas K Ti O and K Ti O .v These prior art alkali metaltitanates are soluble in water or either soluble or decom- 200atmospheres. I After reaction, the mixture is then subjected to extraction,preferably with water or dilute mineral acid, until unreacted alkali, i.e., essentially no more alkali, is extracted therefrom.

The process whereby'the new alkali metal titanates are formed involvesthe reaction in the presence of water of! a titanium compound,preferably a titanium oxide or hydrated oxideQwith analkali metal oxideora suitable basic alkali metal compound, such'as the carbonate orhydroxide, at a temperature of at. least 400 C. and

; pressure of at least 200 atmospheres. In this reaction,

posed byv aqueous acids orba'ses; However, there has been. no report inthe literature of an asbestos-like or fibrous alkali metaltitanatexwhich' is water-insoluble.

. It is an object of this invention to provide fibrous alkali metaltitanates and amethod for their preparation. A further object is toprovide fibrous alkali metal titanates which are water-insoluble.Another-"Object is to provide fibrous alkali metal'titanates in the formof asbestos-like fibers. Other objects will'appear hereinafter. L Theseand other objects of this invention are accomplished by providing newfibrous alkali metal titanates which are water-insoluble and whereinthealkali metal has an atomic number of at least eleven; The alkali metaltitanates of this invention have a fibrous structure in which onedimension of the crystal is longer than the other dimensions by a factorof atleast five and generally ten to one hundred and up to.1000 or more,i. e.,

the ratio of length to width of the crystal at least 5:1 and generally10:1 to 100:1 and up to l000:1 or more. This fibrous product is purifiedand separated from any other alkali metal or titanium compounds bypressure-resistant vessels inert to the reagents present are used. Theratio of charge of alkali metal oxide, e. g., potassium oxide, totitanium oxide, can vary from 1:6

to 12:1, with the preferred ratio being from 3:1 to 8:1."

Thetitanium compound employed. is generally present in finely divided oruniformly dispersed form. The alkali metal compound is generally presentin solution or suspended in Water. The, reaction is generally efiectcdat temperatures of 400 to S00 C. or even higher, with temperatures of600 to 700 C. preferred. The reaction is generally finished in times ofa few hours or less. The new fibrous alkali metal titanates of thisinvention are readily separatedfrom undesired products, such as unusedstarting materials, vby virtue of their insolu'bility and lack ofreactivity to water, dilute and concentrated mineral acids, includinghydrochloric and sulfuricacid, bases such as potassium hydroxide, andaqueous salt solutions. w I

In thefollowing examples, parts are by weight, and all of the reactionsare conducted in sealed, collapsible; platinum vessels which aresubjected to the prescribed physical conditions, in apparatus capable ofoperating under such conditions. These examplesarefor purposes ofillustrationof preferred procedures for the preparation of the novelfibrous alkali vention. i o

I I Example I o p A mixture of 0.1329 part titanium dioxide (anatas'e),

0.0665 part sodium hydroxide (Na O/TiO =1/2) and 0.1665 part water washeated to 625 C. at a pressure of about 2800 atmospheres. Theseconditions were attained in about 25 minutes at which time the heatingwas discontinued and the mixture allowed to return to atmosphericconditions. The entire solid product comprised fibers about 25 micronslong and having a length to diameter ratio of about 100/1. The fibrousproduct was insoluble in aqueous solutions.

. Example II A, mixture of 0.2304 part titanium dioxide (anatase) and0.133 part IO N sodium hydroxide aqueous solution of long fiberswhoseproperties were the same as those scribed in the titanium prior art;Furthermore, the

alkali metal titanates of this invention do not hydrate,

2 i. e., .do not absorb water of crystallization and thus do" notcontain water of crystallization. 7

It has now been found that fibrous as well as waterinsolub1e andnon-hydrated alkali metal titanates can be prepared by reacting in thepresence of water, a water-soluble basic oxygen-containing alkalimetalcompound, such an an alkali metal hydroxide, wherein the alkali metalhas an atomic number of at least eleven, with an oxygen-containingtitanium compound, such as titanium dioxide, in a molar ratio of 1:6 to12:1, calculated as alkali metal oxide to titanium dioxide, at'atemperature of at least 400 C. under pressureofsat least.

(Na O/TiO =l/6) was heated 1.5 hours at 625 C. and 3000 atm. pressure.Upon returning the product to atmospheric conditions it was found tocontain fibrous sodium titanate, of which atleast 5% was in the form ofthe productof Example I.

v Exaniple III A mixture of 0.0250 part titanium dioxide (rutile) and1.05 part 10 N potassium hydroxide aqueous solu tion (K O/TiO =12/ 1)was heated 1.5 hours at 625 C. and 3000 atm. pressure. Upon returningthe mixture to atmospheric conditions, it was found that about of thepotassium tita'nate product was in the form of long fibers which wereinsoluble in aqueous solutions.

. V I Example IV A mixture of 0.16; part titanyl sulfate and 0.35 10 Npotassium hydroxide aqueous solution (K O/TiOSO 1/ 1) I Patented May 6,1958 metal titanates of t i in- Example III.

was heated '1 hour art-625 C. and 3000 atm. pressure. Upon cooling toroom temperature, the entire solid product comprised a fluffy, lightgray water-insoluble asbestoslike material. Individual; fibers wereabout .15 microns Emma w f A mixture of 0.500 part titaniumdioxidelanatase), 2.6parts potassium carbonate (K O/TiO,:3/-l) and 4parts water was heated *2 hours -at- 625' C. and 3000 atmospherespressure. After returning to atmospheric conditionsythe entireproductcomprising fibrous potassium titanate suspeudedyin anaqueous",;alkaline. medium was titrated potentiometrically with astandard solution of hydrochloric acid; It was found that'0ll04 part of.the alkali (as K wasnot available -for-neufl'alization by'the acid andwas therefore combined "with the 0.5 part titania. This corresponds to aratio'of, K Q/TiQ,=1/'S.7 in the,

product. {1 The suspensionwasfiltered and thesolid product I washed anddriedtoobtain 0.045 part long fibers ranging up to 1 cm. in length andabout lmicron in diameter and 0.547' partof mattedshort'fibersless than]mm. in lengthyi. a; Pthese' flexible fibers'were feltedinto a mat.

"The totalweight of product *from part titauia. was

therefore 0. 592 part. Onthe-assrimptiqnthat all of the weight increaseis K o ithe K O/TiO ratio is 1/6.4 in

l the product. Analysis :of the fibrous potassium titanate revealed50.3% titanium and 12.6% ing a KgO/TiO, ratio of 1/ 6.8.

Similar preparations ofpotassium. titanate from potassium earbonateand,anatase were conducted in which the ratio of the. reactants was varied.The results were. as follows: i

potassium indicatmo Tior Ratio in Product Based In Reactants l s NQn-Weight Kand Ti tltratable of Analyses Alkali Product 1 1 1 1/5.8 l/6.61/6.9 sir r rr 116.0 1/6.4 1/7.4

The products were. asbestos-like water-insoluble fibers.

Example VII A mixture of 0.1 pa t tita ium dioxide (mm); 0 32 p r u py hs a s. K33 1 (Ks 1/IiQr=.-

and 0.4 part water was heated 0.5 hour": a t ,625C. and

3000 atm. pressure. After the reaction mixture was returned toatmospheric conditionsyit was found to contain short potassium titanatewater-insoluble fibers having an approximate length of microns and adiameter of 1 micron.

Example VIII" I \A of 0.1 parturanium-mums(muse 6.6. arbonate(RbzO/TiQlfl/l) an 0.9 part water, was heated 3, hours at 625 C. and3000 atm. pressure. The produetcomprised in preponderant amount fiexiblewater insoluble fibers having diameters ranging to less than 1 micronand lengths ranging to over 1000 microns. l. 1

aaaaeao '4 7 Example IX A mixture of 0.1 part titanium dioxide(anatase), 1.222

part cesium carbonate (Cs 0/TiO =3/l) and 0.9 part water was heated 3hours at 625 C. and 3000 atm. pressure. The product comprised, in majoramounts, waterinsoluble fibers of-up to about 200 microns long and about1 micronindiameter.

Example X A mixture of 0.1336 part titania (titanium dioxide) and 1.40part 10 N aqueous potassium hydroxide solution (KgO /TiOy-s-fi/ 1) washeated 1.5 hours at 450 C. and 10.00 atmrpressure. The product comprisedgrayish white, long water-insoluble fibers of potassium titanate.

The new products of this invention are asbestos-like fibrous,non-hydrated,- alkali metal titanates which are water-insoluble andwherein the alkali metal has an atomic number of at least eleven.Chemical analysis of the fibrous alkali metal titanates of thisinvention indicates that :they correspond in chemical composition to the:gen-

' to 7. Determination ofthe non-,titratable alkali in the Pro uctsresulting from ;the process :of this inventionkindica sis :thatumhasavalue :of about .6 in the fibrous alkali metal titanates corresponding.in chemical composition 'to thefulfmula .M,Q(TiQ,),.wherein M is analkali metal of atomic number .of at least eleven. Thus, bydetermination of uonetitratable alkali, the fibrous alkali metalitanates are indicated .to have the general iformula s s eQisi. wherein1M is an alkali metal having atomic number .;of .,at, leastaeleven suchas potassium, sodium,

u idiumand cesium. 0futhe alkali metals, sodium and potassiumare-cheaper. and more readily .available'thnn the other alkali. metalsand z-thereforemost preferred.

These newiproducts .arencharacterized by their insolubilityaud lack ofreactivitywith water and'aqueous solutions of mineraLacida-bases or.salts. They do not .form hydrates ji. .e,.. :absorb water ofcrystallization. The titanates of-alkali metals. of atomic number of 11or greate ilv e,, sodium, potassium, rubidium and cesium, are.obtaineddn the .forrnrof' fibers, i. e., asbestos-like, and have alength to diameter ratio of at least 5:1 and usual ly of at least .10, 1. .A'SaShOWll in .the examples, .thelength is,generally .10 to .1000times the diameter of the fiber. As shown by ExampleiVHI. there areobtained .by the process of this ,invention alkali metal titanates intheform of water-insoluble flexible :fibers having a ratio of lengthtoldiameterranging to over l000:1.

In the preparation of the new alkali metal titanates, an alkali.metalcornpound such asthe carbonate or by droxide is generallyemployedalthough other waterssoluble compqunds can be used, c. .g., :analkali metal phos- Phate. The alkali metal icompofund is-preferablybasic es .-a basic reaction with water. Particularly useful arethealkllimetal hydroxides andcarbonates, i. .e., basicQEYEn-wntainiugalkali metal compounds which are soluble in water orwhich form the alkali metalzhydrosride in aqueous; solution.

Thetitanium source can be a titanium oxide, or salt.Particularlysuitable in viewof its availability isr'titanium dioxide.However, soluble titanium compounds-sucks:-

it nyls lfalc or lower titanates can be employed.

It is to be noted The new products of or bases. Advantage is taken ofthis property in the purification of the new titanates since alkalimetal hydroxides, carbonates or other salts are water soluble. In viewof the ease of removal of other alkali'metal compounds than thosecombined'with titanium in the manner required for the new products ofthis invention, the alkali metal starting compound can be, and usuallyis, employed in slight'excess over the theoretical value; When titaniumdioxide is present in the final product, it is generally removed bytaking advantage of its greater density and higher sedimentation rate.

The reaction between the titanium and alkali metal compounds is effectedattemperatures of at least'400 C. and generally less than 800 C. withthe temperature preferably at 600 to 700 C. The reaction requires thepresence of water. To retain water in the reaction media under theseconditions necessitates the use of pressures of at least 200atmospheres, and generally 500 atmospheres or more, as well as equipmentthat will withstand the conditions and reagents employed. The upperpressure limit is dependent only on the equipment employed. Althoughpressures of 10,000 atmospheres can be used, such pressures requirestrong and expensive equipment. Pressures of the order of 1000 to 4000atmospheres are relatively easy to maintain and these pressures arepreferred. The reaction time is generally short, e. g., a few minutes toa few hours.

The new asbestos-like fibrous alkali 'metal titanates of this inventionare inert to many corrosive chemical reagents. For example, thesetitanates are insoluble in boiling 50% caustic, insoluble in aqueousacids such as sulfuric acid and concentrated hydrochloric acid, andunattacked by chlorine.

The fibrous alkali metal titanates are particularlyuseful inapplications where the inertness and physical properties of anabsestos-type material are required, e. g., in reinforcing agents, infibers or papers and as insulation material.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that this invention is not limited to the specificembodiments thereof except as defined in the appended claims.

We claim: 8 v

1. A method for preparing an absestos-like fibrous,

'water-insoluble alkali metal titanate which comprise reacting in thepresence of water, a water-soluble basic oxygen-containing alkali metalcompound, wherein the alkali metal has an atomic number of at leasteleven, with an oxygen-containingtitanium compound in a molar ratio of1:6 to 12:1, calculated as alkali metal oxide to titanium dioxide, at atemperature of at least 400 C. under a pressure of at least 200atmospheres, and separating as the resulting product an alkali metaltitanate in the form of water-insoluble, non-hydratable, flexiblefibers.

2. A method for preparing'an asbestos-like fibrous, Water-insolublealkali metal titanate which comprises reacting in the presence of water,an alkali metal hydroxide, wherein the alkali metal has an atomic numberof at least eleven, with titanium dioxide in a molar ratio of 1:1 to8:1, calculated as alkali metal oxide to titanium dioxide, at atemperature of 400 C. to 800 C. under a pressure of 500 to 4000atmospheres, and separating as the resulting product an alkali metaltitanate in the form of water-insoluble, non-hydratable, flexiblefibers.

3. A method for preparing an absestos-like fibrous, water-insolublealkali metal titanate as set forth in claim 1, wherein said alkali metalcompound is an alkali metal hydroxide in which the alkali metal has anatomic number of at least 11.

4. A method for preparing an asbestos-like fibrous, water-insolublealkali metal titanate as set forth in claim 1, wherein said alkali metalcompound is an alkali metal thealkali metal has an atomic number of 1:6to 12:1, calculated as alkali metal oxide to sodium'titanate in the formof water-insoluble, nontitanium dioxide, at a temperature of 400 to 800]C. under a pressure of 500 to 4000 atmospheres, and separating as theresulting product an alkali metal titanate in the form ofwater-insoluble, non-hydratable, flexible fibers.

7. A method for preparing an asbestos-like fibrous,

water-insoluble sodium titanate which comprises reacting in thepresenceof'water, sodium hydroxide with titanium dioxide in a molarratio of 1:6 to 12:1, calculated as sodium oxide to titanium dioxide, ata temperature .of

600 to- 700 C., undera pressure of l000'to 4000 atmospheresyandseparating as the resulting product sodium titanate in the form ofwater-insoluble, nonhydratable, flexible fibers.

' 8. A method for preparing an asbestos-like fibrous, water-insolublepotassium titanate which comprises reacting in the presence of water,potassium hydroxide with 'titanium dioxide in a molar ratio of 1:6 to1221,:

calculated as potassium oxide to titanium dioxide, ata temperature of600 to 700 C., under a pressure .of 1000 to 4000 atmospheres, andseparating as theresulting product potassium titanate in the form ofwaterinsoluble, non-hydratable, flexible fibers.

9. A method for preparing an asbestos-like fibrous, Water-insolublealkali metal titanate which comprises reacting in the presence of water,an alkali metal carbonate wherein the alkali'metal has an atomic numberof at least 11, with titanium dioxide in a molar ratio of 1:6

to 12:1, calculated as alkali metal oxide to titanium dioxide, at atemperature of 400 to 800 C. under a pressure ,of 500 to 4000atmospheres, and separating as the resulting product an alkali metaltitanate in the form of water-insoluble, non-hydratable, flexiblefibers.

10. A method for preparing an asbestos-like fibrous,

water-insoluble sodium titanate which comprises reactmg in the presenceof water, sodium carbonate with titanium dioxide in a molar ratio of 1:6to 12:1, calculated as sodium oxide to titanium dioxide, at atemperature of 600 to 700 C., under a pressure of 1000 to 4000'hydratable, flexible fibers.

'ing in the presence of water, potassium carbonate with 1 11. A methodfor preparing an asbestos-like fibrous, water-insoluble potassiumtitanate which comprises reacttitanium dioxide in a molar ratio of 1:6to 12:1, calculated as potassium oxide to titanium dioxide, at atempera- I ture of 600 to 700 C., under a pressure of 1000 to 4000atmospheres, and separating as the resulting product potassium titanatein the form of water-insoluble,

non-hydratable, flexible fibers.

12. As a new inorganic fibrous material, alkali metal titanatecrystalline fibers each having a ratio of length to width of at least10:1, and each being sufficiently flexible to be felted, said fibersbeing insoluble in water, not absorbing water of crystallization to forma hydrate, and having the general formula M O-(TiO wherein M is analkali metal having an atomic number of at least 11 and n has a value offrom 6 to 7.

13. As a new inorganic fibrous material, sodium titanate crystallinefibers each having a ratio of length to width of at least 10:1, and eachbeing sufliciently flexible to be felted, said fibers being insoluble inwater, not absorbing water of crystallization to form a hydrate,

to width of vat least 'lOzl jand each being sufficiently flexible to be"felted, said fibers being insoluble in water, not absorbing water ofcrystallization. to form a hydrate, and ha'vin'g the general formula MO-(TiO wherein M is rubidium andn has a value of fro m 6 to 7.

t a I new inorganic. fibrous: material, cesium titanate flcr y stallinefibers. each having a ratio. of length to width of at least 10:1, and:each being sufficiently ilef xible to. be felted, said fibers beinginsoluble in water,

a s i water f Cr st l ion to fame hyd e. ancihavi s the general fo m lazQ (non... whe ei M is ce'siurn and nfhas a value offfrom ,to 7.

17. An inorganic flexible, fiber: havingyta ratio of length to width ofat least :1consisting of an alkali metal; titanate fiber which issufficiently flenibleto' be f lted. and which is insoluble in water,doesnot absorb water of crystallization, to form ahydrate; and havingthe general: formula p-(11.09,, wherein M, is an alk alijme't'al havingan atomic number of at least 11 and n hasa value of from.6 to 7.

18.f An inorganic flexible fiber having a ratio of length' to width of"at least 10:1 consistingof a titanate 'fiberflwhich is sufficientlyflexible to be felted and which is insolublejin'water, does not absorb:water of crystallization totform ahydrate, i dhaving the gqneral,formula MQQEKTiQQm wherein M is sodium andnhas a value ofifrom 6 to 7.

g An inorganic flexible. fiber having a .ratio of length towidthof atleast 10:1 consistingof a potassium titanate fiber. which issufliciently flexible tobe felted and whichis insoluble in water,doesnot absorb water of crystallization to form a hydrate, and havingthe general formula M,o-(Tio,).,,, wherein M is potassium and n hasa'value of fror'n'6 to 7. I g

20. An inorganic flexible fiber having a ratio of length to widthof atleast 10:1 consisting of a rubidium titanate fiber which issufliciently'flexible to be felted .and which is insoluble in water,doesnot absorb water of crystalliza- '22 A new inorganic fibrousmaterial comprising.

alkalimetal titanate crystalline f bers each having a ratio .of lengthto width of at least 10; 1, and each being it sufliciently flexible tobe felted,said fibers being insoluble in water, not absorbing water ofcrystallization to form a hydrate, ,and having the general formula M' Tio wherein M is an alkali metal having an atomic number of at least 11.

'23. A new inorganic fibrous material comprising potassium titanatecrystalline fibers each having a ratio of length to width of at least10:1, and each being sufficiently flexible to be felted, said fibersbeingqinsoluble inwater, not absorbing water of crystallization to forma hydrate, and having the general formula MgTioom, wherein M ispotassium.

24. Inorganic flexible fibers,. each having a ratio of lengthto width ofat least 10:1 and consistiugof an alkali metal titanate fiber which issufficiently flexible to be felted and which ,is insoluble in water,does not absorb water-of crystallization to form a hydrate, and havingthe general formula Mfli o wherein M is an alkali metal having an.atomic number of at least 11.

2 5. Inorganic flexible fibers, each having a ratio of length to widthof at vl east .1 0:l and consisting of an alkali metal titanate fiberwhich is sufficiently flexible to be felted and which is insoluble :inwater, does not absorb water of crystallization to form a hydrate, andhaving the general formula M Ti O wherein M is potassium.

26. An insulating composition comprising amass of metal Jtitanatecrystalline fibers which are sufliciently flexible to be felted andwhichare insoluble in water, do not absorb water of crystallization to form ahydrate, and have the general formula M 13 0 wherein M is an alkalimetal having an atomic number of at least '11.

27. An insulating composition comprising amass of M potassium titanatecrystalline fibers which are sufficiently flexible to be felted andwhich are insoluble in water, do not absorb water of crystallization toform a hydrate and have the general formula iM Ti O wherein M ispotassium.

References Cited in the file of this. patent UNITED STATES PATENTS OTHERREFERENCES Barksdale: Titanium," 1949, pages 97-101, Ronald Press Co.,N, Y. C.

Mellor: Comprehensive Treatise von Inorganic and Theoretical Chemistry,vol. 7, page 51, Longmanns, Green ,8; CQ,,N. Y. 0., 19 27.

Gmelin Kraut: Handbuch der Anorganischen Chemie Band 3, Abt. 1, page 84,Carl Winters Universtatsbuchhandlung, 1912,

1. A METHOD FOR PREPARING AN ABSESTOS-LIKE FIBROUS WATER-INSOLUBLEALKALI METAL TITANATE WHICH COMPRISE REACTING IN THE PRESENCE OF WATER,A WATER-SOLUBLE BASIC OXYGEN-CONTAINING ALKALI METAL COMPOUND, WHEREINTHE ALKALI METAL HAS AN ATOMIC NUMBER OF AT LEAST ELEVEN, WITH ANOXYGEN-CONTAINING TITANIUM COMPOUND IN A MOLAR RATIO OF 1:6 TO 12:1,CALCULATED AS ALKALI METAL OXIDE TO TITANIUM DIOXIDE, AT A TEMPERATUREOF AT LEAST 400*C. UNDER A PRESSURE OF AT LEAST 200 ATMOSPHERES, ANDSEPARATING AS THE RESULTING PRODUCT AN ALKALI METAL TITANATE IN THE FORMOF WATER-INSOLUBLE, NON-HYDRATABLE, FLEXIBLE FIBERS.
 12. AS A NEWINORGANIC FIBROUS MATERIAL, ALKALI METAL TITANATE CRYSTALLINE FIBERSEACH HAVING A RATIO OF LENGTH TO WIDTH OF AT LEAST 10:1, AND EACH BEINGSUFFICIENTLY FLEXIBLE TO BE FELTED, SAID FIBERS BEING INSOLUBLE INWATER, NOT ABSORBING WATER OF CRYSTALLIZATION TO FORM A HYDRATE, ANDHVING THE GENERAL FORMULA M2O9(TIO2)N, WHEREIN M IS AN ALKALI METALHAVING AN ATOMIC NUMBER OF AT LEAST 11 AND N HAS A VALUE OF FROM 6 TO 7.